Hi all, I just joined. I'm currently a double major in biology and psychology, so I love science.

A discussion came up on another forum I visit where somebody claimed we do not need animals and therefore, we are not responsible for them.

Obviously I disagree and I'm pretty sure that if all the animals in the world were killed off, it would create a major upset in the ecosystem. Can anybody here give me some examples of some of the things that humankind would face if there were no animals?

Right now the main one that is coming to mind is waste management. Without animals aiding in the decomposition of our waste products, we would become overwhelmed, and I'd also assume that illness and death from disease would go up. Another one would be insect control, which would in turn likely cause an increase in cases of insect born diseases and illnesses like Lyme and Malaria.

What am I missing?

Anyway, I look forward to getting to know the regulars here and discussing science related topics

I dont think you worded your question right, are you talking wild animals or are you including domesticated animals? I'm going to assume you mean all animals.

-First of all you have mass starvation(rice can only sustain a race for so long),

-Bacteria(Kingdom:Monera) and Fungi(Kingdom:Fungi...) are mostly responsible for the decomposition of organic substances so our waste would not be too much of a problem.

-Insects are animals, so if all animals are gone you wont have to worry about insects carrying malaria.

-After this human semi extinction plants high in protein(e.g oats) would then have to be produced by the richer countries who survived (keep in mind the prices would be quadrupled). But even then i don't think(correct me if im wrong) we would be able to get every amino acid that we need out of a source like this without farming many different types of nuts and cereals.

-The dramatic drop would leave populations with a much smaller genetic variance which would leave them more vulnerable to virus and bacterial outbreaks.

So many factors would come into this that i don't think even the most complex computer model would be able to predict any kind of result of such a dramatic change to the worlds ecosystems.My guess would be game over for humans. But thats only a guess.

P.S I would definitely like to hear from someone studying molecular biology on the issue of amino acids and essential fats etc. - whether we can get all that we need from plants. I have heard vegetarians tell me that we can get all that we need from plants but i dunno whether this is true.

A wise man once said to me:"Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life."

Mass starvations? Hardly; growing sufficient food to feed the world is currently *hampered* by the demand for livestock and meat. In fact, worldwide, more starvation is caused by growing food inefficiently through livestock rather than arable farming.

If Animals were to disappear, we would lose a convenient but largely unhealthy staple of the Western diet, but there are billions worldwide who rarely if ever consume meat anyway; it's too expensive for most without government subsidies.

Of greater concern is the loss of insects; without pollinators, much of our farming would collapse. Wind-pollinated grains would continue to provide staple food, but artificial pollination of each and every flower would be needed to maintain standard crops.

That's the real source of the nigh-extinction scenario. However, given a few years of developing GM crops that develop fruit even if not fertilised, we could establish new breeds of plants to feed who remained. Hopefully we'd have the sense to make them genetically diverse too, to avoid the sort of extinction scenarios we're already facing with the Banana.

I'm not sure if the person who made the statement was including insects or not, I assumed she wasn't. Same with domestic vs wild. She just made a general comment.

Also, mass starvation? True, a race probably couldn't live long on rice alone, but we harvest many other fruits, vegetables, nuts and grains. Vegans can get nutritional fulfillment from non animal products as long as they are aware of the nutritional values of the foods they are eating and know how much they need.

Another one I just thought of would be pollination. If she is indeed including insects, then we have a problem there.

Someone mentioned this before, but without protists and such that decompose,organic compounds would not be able to be recycled, and everything would be locked up as waste. Why would a tree rot, or a dead animal? All the compounds and nutrients that make them up would not be put back into the ecosystem.

Billions world wide who don't eat meat? i very much doubt it...Maybe those who live in more developed countries and have access to specialized plant protein formulas and are able to get artificially produced multivitamins which contain all the necessary vitamins like Niacin, Vitamin B12, Vitamin D which are essential for our health and only come from meat and products of animals(e.g milk eggs etc.), but it is those in lesser developed countries(around 50 countries' individuals earn less than 750USD per year hundreds more which earn just above 900USD) which would suffer, the human body has developed over millions of years to eat meat and we rely on it, without the nutrients we get from meat in these lesser developed countries children would not develop properly and the men that have to work on farms would eventually be too weak to.Without meat(or eggs milk etc.), or any substitute for it the human race would be nothing. Its is only where these substitutes have been created that it would stand a chance.

A wise man once said to me:"Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life."

I don't think I've seen this reply yet: It doesn't really matter to humans, because we are part of the animal kingdom. We would die, too.

But, I will assume that you only meant the OTHER animals and say that whoever thinks that we don't need animals obviously didn't do his/her research. Being part of the animal kingdom ourselves, we depend on some of these animals. Even the ones that we DON'T depend on directly, we are still connected to and dependent on them in some way.